A systematic, updated review on the antidepressant agomelatine focusing on its melatonergic modulation

Objective:

To present an updated, comprehensive review on clinical and pre-clinical studies on agomelatine.

Method:

A MEDLINE, Psycinfo and Web of Science search (1966-May 2009) was performed using the following keywords: agomelatine, melatonin, S20098, efficacy, safety, adverse effect, pharmacokinetic, pharmacodynamic, major depressive disorder, bipolar disorder, Seasonal Affective Disorder (SAD), Alzheimer, ADHD, Generalized Anxiety Disorder (GAD), Panic Disorder (PD), Obsessive-Compulsive Disorder (OCD), anxiety disorders and mood disorder.

Study collection and data extraction:

All articles in English identified by the data sources were evaluated. Randomized, controlled clinical trials involving humans were prioritized in the review. The physiological bases of melatonergic transmission were also examined to deepen the clinical comprehension of agomelatine’ melatonergic modulation.

Data synthesis:

Agomelatine, a melatonergic analogue drug acting as MT₁/MT₂ agonist and 5-HT_2C antagonist, has been reported to be an effective antidepressant therapy.

Conclusions:

Although a bias in properly assessing the “sleep core” of depression may still exist with current screening instruments, therefore making difficult to compare agomelatine’ efficacy to other antidepressant ones, comparative studies showed agomelatine to be an intriguing option for depression and, potentially, for other therapeutic targets as well.     

Randomized Controlled Trials of Add-On Antidepressants in Schizophrenia

Background:

Despite adequate treatment with antipsychotics, a substantial number of patients with schizophrenia demonstrate only suboptimal clinical outcome. To overcome this challenge, various psychopharmacological combination strategies have been used, including antidepressants added to antipsychotics.

Methods:

To analyze the efficacy of add-on antidepressants for the treatment of negative, positive, cognitive, depressive, and antipsychotic-induced extrapyramidal symptoms in schizophrenia, published randomized controlled trials assessing the efficacy of adjunctive antidepressants in schizophrenia were reviewed using the following parameters: baseline clinical characteristics and number of patients, their on-going antipsychotic treatment, dosage of the add-on antidepressants, duration of the trial, efficacy measures, and outcomes.

Results:

There were 36 randomized controlled trials reported in 41 journal publications (n=1582). The antidepressants used were the selective serotonin reuptake inhibitors, duloxetine, imipramine, mianserin, mirtazapine, nefazodone, reboxetin, trazodone, and bupropion. Mirtazapine and mianserin showed somewhat consistent efficacy for negative symptoms and both seemed to enhance neurocognition. Trazodone and nefazodone appeared to improve the antipsychotics-induced extrapyramidal symptoms. Imipramine and duloxetine tended to improve depressive symptoms. No clear evidence supporting selective serotonin reuptake inhibitors’ efficacy on any clinical domain of schizophrenia was found. Add-on antidepressants did not worsen psychosis.

Conclusions:

Despite a substantial number of randomized controlled trials, the overall efficacy of add-on antidepressants in schizophrenia remains uncertain mainly due to methodological issues. Some differences in efficacy on several schizophrenia domains seem, however, to exist and to vary by the antidepressant subgroups—plausibly due to differences in the mechanisms of action. Antidepressants may not worsen the course of psychosis. Better designed, larger, and longer randomized controlled trials are needed.     

Chronic agomelatine treatment corrects behavioral, cellular, and biochemical abnormalities induced by prenatal stress in rats

Rationale and objectives

The rat model of prenatal restraint stress (PRS) replicates factors that are implicated in the etiology of anxious/depressive disorders. We used this model to test the therapeutic efficacy of agomelatine, a novel antidepressant that behaves as a mixed MT1/MT2 melatonin receptor agonist/5-HT_2c serotonin receptor antagonist.

Results

Adult PRS rats showed behavioral, cellular, and biochemical abnormalities that were consistent with an anxious/depressive phenotype. These included an increased immobility in the forced swim test, an anxiety-like behavior in the elevated plus maze, reduced hippocampal levels of phosphorylated cAMP-responsive element binding protein (p-CREB), reduced hippocampal levels of mGlu2/3 and mGlu5 metabotropic glutamate receptors, and reduced neurogenesis in the ventral hippocampus, the specific portion of the hippocampus that encodes memories related to stress and emotions. All of these changes were reversed by a 3- or 6-week treatment with agomelatine (40?C50?mg/kg, i.p., once a day). Remarkably, agomelatine had no effect in age-matched control rats, thereby behaving as a ??disease-dependent?? drug.

Conclusions

These data indicate that agomelatine did not act on individual symptoms but corrected all aspects of the pathological epigenetic programming triggered by PRS. Our findings strongly support the antidepressant activity of agomelatine and suggest that the drug impacts mechanisms that lie at the core of anxious/depressive disorders.     

Clinical efficacy of agomelatine in depression: the evidence

Despite the advances of recent decades, there is still an urgent need for antidepressants with improved efficacy, safety and tolerability. Agomelatine is a new antidepressant with an innovative pharmacological profile. It is the first melatonergic antidepressant, and is a potent agonist of melatonin receptors (MT1 and MT2) with 5-HT2C antagonist properties. The efficacy of 25 mg/day agomelatine in treating major depressive disorder (MDD) has been demonstrated in a number of placebo-controlled studies. Evidence of improvement in depressive symptoms was observed in a dose-ranging study in which 25 mg/day agomelatine was significantly better than placebo, whatever the rating scale used (Hamilton Rating Scale for Depression, Clinical Global Impression, and Montgomery-Asberg Depression Rating Scale). These results have been confirmed in two similarly designed placebo-controlled studies. Agomelatine also produces a significant improvement in anxiety compared to placebo, according to Hamilton Rating Scale for Anxiety scores. The efficacy of agomelatine has been studied in subpopulations with more severe depression, demonstrating its efficacy in these difficult-to-treat patients. In view of the available data on agomelatine, this antidepressant can be regarded as an innovative treatment for MDD patients, offering a new approach in the management of depressed patients.     

Agomelatine (S20098) modulates the expression of cytoskeletal microtubular proteins, synaptic markers and BDNF in the rat hippocampus, amygdala and PFC

Rationale

Agomelatine is described as a novel and clinical effective antidepressant drug with melatonergic (MT₁/MT₂) agonist and 5-HT_2C receptor antagonist properties. Previous studies suggest that modulation of neuronal plasticity and microtubule dynamics may be involved in the treatment of depression.

Objective

The present study investigated the effects of agomelatine on microtubular, synaptic and brain-derived neurotrophic factor (BDNF) proteins in selected rat brain regions.

Methods

Adult male rats received agomelatine (40?mg/kg?i.p.) once a day for 22?days. The pro-cognitive effect of agomelatine was tested in the novel object recognition task and antidepressant activity in the forced swimming test. Microtubule dynamics markers, microtubule-associated protein type 2 (MAP-2), phosphorylated MAP-2, synaptic markers [synaptophysin, postsynaptic density-95 (PSD-95) and spinophilin] and BDNF were measured by Western blot in the hippocampus, amygdala and prefrontal cortex (PFC).

Results

Agomelatine exerted pro-cognitive and antidepressant activity and induced molecular changes in the brain areas examined. Agomelatine enhanced microtubule dynamics in the hippocampus and to a higher magnitude in the amygdala. By contrast, in the PFC, a decrease in microtubule dynamics was observed. Spinophilin (dendritic spines marker) was decreased, and BDNF increased in the hippocampus. Synaptophysin (presynaptic) and spinophilin were increased in the PFC and amygdala, while PSD-95 (postsynaptic marker) was increased in the amygdala, consistent with the phenomena of synaptic remodelling.

Conclusions

Agomelatine modulates cytoskeletal microtubule dynamics and synaptic markers. This may play a role in its pharmacological behavioural effects and may result from the melatonergic agonist and 5-HT_2C antagonist properties of the compound.     

A placebo-controlled study of tropisetron added to risperidone for the treatment of negative symptoms in chronic and stable schizophrenia

Rational

A growing body of evidence illustrates that 5-HT3 receptor antagonist drugs may be of benefit in the treatment of negative symptoms in schizophrenia.

Objective

The objective of this study was to assess the efficacy and tolerability of tropisetron add-on to risperidone on negative symptoms in patients with chronic stable schizophrenia.

Methods

In a double-blind, placebo-controlled 8-week trial, 40 patients with chronic schizophrenia who were stabilized on risperidone were randomized into tropisetron or placebo add-on groups. Psychotic symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) every 2 weeks. Furthermore, extrapyramidal and depressive symptoms as well as side effects were assessed. The primary outcome measure was the difference in change from baseline of negative subscale scores between the two groups at week 8.

Results

Tropisetron resulted in greater improvement of the total PANSS scores [F(1.860,70.699)?=?37.366, p?<?0.001] as well as negative scores [F(2.439,92.675)?=?16.623, p?<?0.001] and general psychopathology [F(1.767,67.158)?=?4.602, p?=?0.017], but not positive subscale scores [F(1.348, 51.218)?=?0.048, p?=?0.893] compared to placebo. In a multiple regression analysis controlling for positive, extrapyramidal, and depressive symptoms, treatment group (standardized β?=??0.640) significantly predicted changes in primary negative symptoms. The side effect profile did not differ significantly between the two groups.

Conclusion

Tropisetron add-on to risperidone improves the primary negative symptoms of patients with chronic stable schizophrenia.     

Antidepressant Compounds Can Be Both Pro- and Anti-Inflammatory in Human Hippocampal Cells

Background:

The increasingly recognized role of inflammation in the pathogenesis and prognosis of depression has led to a renewed focus on the immunomodulatory properties of compounds with antidepressant action. Studies have, so far, explored such properties in human blood samples and in animal models.

Methods:

Here we used the more relevant model of human hippocampal progenitor cells exposed to an inflammatory milieu, induced by treatment with IL-1β. This increased the levels of a series of cytokines and chemokines produced by the cells, including a dose- and time-dependent increase of IL-6. We investigated the immunomodulatory properties of four monoaminergic antidepressants (venlafaxine, sertraline, moclobemide, and agomelatine) and two omega-3 polyunsaturated fatty acids (n-3 PUFAs; eicosapentanoic acid [EPA] and docosahexanoic acid [DHA]).

Results:

We found that venlafaxine and EPA were anti-inflammatory: venlafaxine decreased IL-6, with a trend for decreases of IL-8 and IP-10, while EPA decreased the levels of IL-6, IL-15, IL-1RA, and IP-10. These effects were associated with a corresponding decrease in NF-kB activity. Unexpectedly, sertraline and DHA had pro-inflammatory effects, with sertraline increasing IFN-α and IL-6 and DHA increasing IL-15, IL-1RA, IFN-α, and IL-6, though these changes were also associated with a decrease in NF-kB activity, suggesting distinct modes of action. Agomelatine and moclobemide had no effect on IL-6 secretion.

Conclusions:

These observations indicate that monoaminergic antidepressants and n-3 PUFAs have distinctive effects on immune processes in human neural cells. Further characterization of these actions may enable more effective personalization of treatment based on the inflammatory status of patients.     

S100B Serum Levels Predict Treatment Response in Patients with Melancholic Depression

Background:

There is an ongoing search for biomarkers in psychiatry, for example, as diagnostic tools or predictors of treatment response. The neurotrophic factor S100 calcium binding protein B (S100B) has been discussed as a possible predictor of antidepressant response in patients with major depression, but also as a possible biomarker of an acute depressive state. The aim of the present study was to study the association of serum S100B levels with antidepressant treatment response and depression severity in melancholically depressed inpatients.

Methods:

After a wash-out period of 1 week, 40 inpatients with melancholic depression were treated with either venlafaxine or imipramine. S100B levels and Hamilton Depression Rating Scale (HAM-D) scores were assessed at baseline, after 7 weeks of treatment, and after 6 months.

Results:

Patients with high S100B levels at baseline showed a markedly better treatment response defined as relative reduction in HAM-D scores than those with low baseline S100B levels after 7 weeks (P=.002) and 6 months (P=.003). In linear regression models, S100B was a significant predictor for treatment response at both time points. It is of interest to note that nonresponders were detected with a predictive value of 85% and a false negative rate of 7.5%. S100B levels were not associated with depression severity and did not change with clinical improvement.

Conclusions:

Low S100B levels predict nonresponse to venlafaxine and imipramine with high precision. Future studies have to show which treatments are effective in patients with low levels of S100B so that this biomarker will help to reduce patients’ burden of nonresponding to frequently used antidepressants.     

Paliperidone: the evidence of its therapeutic value in schizophrenia

Introduction:

Paliperidone, the 9-hydroxy metabolite of risperidone, is a second-generation antipsychotic that was recently approved for the treatment of schizophrenia. It is marketed as an improvement over risperidone, but is likely to be considerably more costly when risperidone is no longer protected by patent.

Aims:

To review the evidence for the clinical impact of paliperidone in the treatment of patients with schizophrenia, particularly in contrast to risperidone.

Evidence review:

Paliperidone is primarily metabolized and excreted renally, and thus may be of particular utility for patients with hepatic impairment. There is clear evidence that paliperidone is more efficacious than placebo in reducing the positive and negative symptoms of schizophrenia. In patients with schizophrenia, paliperidone has been shown to stabilize acute psychotic symptoms. There is some evidence that it can prevent relapse in stabilized patients. Studies on the cost effectiveness of paliperidone are needed. Most importantly, there are no trials comparing paliperidone directly with other second-generation antipsychotics.

Place in therapy:

Until direct efficacy and cost effectiveness comparisons are made with risperidone, it is difficult to justify paliperidone use over risperidone. It will become even harder to justify when risperidone becomes available as a less expensive generic medication.     

A Methionine-Induced Animal Model of Schizophrenia: Face and Predictive Validity

Background:

Modulating the methylation process induces broad biochemical changes, some of which may be involved in schizophrenia. Methylation is in particular central to epigenesis, which is also recognized as a factor in the etiology of schizophrenia. Because methionine administration to patients with schizophrenia has been reported to exacerbate their psychotic symptoms and because mice treated with methionine exhibited social deficits and prepulse inhibition impairment, we investigated whether methionine administration could lead to behavioral changes that reflect schizophrenic symptoms in mice.

Methods:

l-Methionine was administered to mice twice a day for 7 days.

Results:

We found that this treatment induces behavioral responses that reflect the 3 types of schizophrenia-like symptoms (positive, negative, or cognitive deficits) as monitored in a battery of behavioral assays (locomotion, stereotypy, social interaction, forced swimming, prepulse inhibition, novel object recognition, and inhibitory avoidance). Moreover, these responses were differentially reversed by typical haloperidol and atypical clozapine antipsychotics in ways that parallel their effects in schizophrenics.

Conclusion:

We thus propose the l-methionine treatment as an animal model recapitulating several symptoms of schizophrenia. We have established the face and predictive validity for this model. Our model relies on an essential natural amino acid and on an intervention that is relatively simple and time effective and may offer an additional tool for assessing novel antipsychotics.     

Which Rating Scales are Regarded as ‘The Standard’ in Clinical Trials for Schizophrenia? A Critical Review

Background

This paper reviewed which rating scales past studies adopted as an outcome measure in clinical trials for schizophrenia, for which a consensus has been lacking.

Methods

A PubMed search was conducted using keywords ‘outcome’, ‘rating scales’, and ‘schizophrenia’. Studies published in 1999, 2004 and 2009 were examined to globally see if a trend has changed over the last decade.

Results

One-hundred fifty articles were inspected. As for psychopathology, the positive and negative syndrome scale (PANSS) has been by far the most frequently utilized scale (46%, 79%, and 78% in the respective years), followed by the brief psychiatric rating scale. Affective/anxiety symptoms have been only rarely recorded. Extrapyramidal symptoms have been assessed mostly with the Simpson Angus scale (SAS), more frequently in combination with the abnormal involuntary movement scale (AIMS) and Barnes akathisia scale (BARS) recently. Non-motor adverse effects have been typically reported without a usage of formal rating scales. Depending on the interest of investigation, other critical domains of the illness including functioning, cognition and subjective perspectives have been sporadically reported through the rating scales. The assessment scales were similarly utilized across the years, except for a numerical rise in scale utilization to rate the latter three domains in 2009.

Conclusions

The PANSS and set of AIMS, BARS and SAS, which are expected to take about 60 minutes to complete, are frequently utilized and may be regarded as a ‘standard’ in clinical trials for schizophrenia. Clinical implication of the findings and practical challenges with the existing scales are discussed.     

Focus on agomelatine

Abstract

Background:

Agomelatine is a novel antidepressant with agonist activity at melatonin receptors (MT₁ and MT₂), and antagonistic effects at the 5HT_2c serotonin receptor.     

Comparison of agomelatine and escitalopram on nighttime sleep and daytime condition and efficacy in major depressive disorder patients

Agomelatine, an MT1/MT2 receptor agonist and 5-HT2C receptor antagonist antidepressant, is known to have beneficial effects on subjective sleep in major depressive disorder patients. This international multicenter, randomized, double-blind study compared the effects of agomelatine (25-50 mg/day) and escitalopram (10-20 mg/day) on sleep polysomnographic parameters in major depressive disorder patients treated up to 24 weeks. A total of 138 outpatients were randomly allocated to agomelatine (n=71) or escitalopram (n=67). Treatment with agomelatine was associated with a reduction in sleep latency from week 2 onward. The difference between treatments was significant on all evaluations. Rapid eye movement latency was increased with escitalopram compared with agomelatine, with significant between-group differences at every visit. Agomelatine preserved the number of sleep cycles, whereas it was decreased with escitalopram with significant between-group differences at every visit. Assessments on visual analogue scales indicated that treatment with agomelatine improved morning condition, and reduced daytime sleepiness compared with escitalopram.17-item Hamilton depression rating scale total score was reduced in both groups, agomelatine was statistically noninferior to escitalopram at 6 weeks. Both treatments were well tolerated. This study showed that the clinical effects of agomelatine on sleep and wake parameters are different from that of escitalopram.     

Effect of pharmacist intervention on improving antidepressant medication adherence and depression symptomology: A systematic review and meta-analysis

Background

Depression is a widespread disease with effective pharmacological treatments, but low medication adherence. Pharmacists play a key role in supporting medication adherence in patients with depression given their accessibility to patients.

Agomelatine,a melatonin agonist with antidepressant properties

Agomelatine (β-methyl-6-chloromelatonin), which is structurally homologous to melatonin, is a potent agonist of melatonin MT1 and MT2 receptors as well as an antagonist of serotonin 5-HT_2C receptors. Agomelatine appears to improve sleep without causing daytime sedation. It has not been found to be associated with sexual side effects and discontinuation symptoms. Three placebo-controlled trials, one of them a dose finding study and two of them pivotal trials, suggest that agomelatine is an antidepressant at doses of 25 – 50 mg/day. Agomelatine appears to be well tolerated, without sexual or cardiac adverse effects, weight gain or discontinuation syndromes. Animal studies suggest a possible neuroprotective action of agomelatine, although there are more data in favor of an anxiolytic effect. Substantially more research is needed to establish its role in the treatment of mood and circadian rhythm disorders.     

Increasing Endocannabinoid Levels in the Ventral Pallidum Restore Aberrant Dopamine Neuron Activity in the Subchronic PCP Rodent Model of Schizophrenia

Background:

Schizophrenia is a debilitating disorder that affects 1% of the US population. While the exogenous administration of cannabinoids such as tetrahydrocannabinol is reported to exacerbate psychosis in schizophrenia patients, augmenting the levels of endogenous cannabinoids has gained attention as a possible alternative therapy to schizophrenia due to clinical and preclinical observations. Thus, patients with schizophrenia demonstrate an inverse relationship between psychotic symptoms and levels of the endocannabinoid anandamide. In addition, increasing endocannabinoid levels (by blockade of enzymatic degradation) has been reported to attenuate social withdrawal in a preclinical model of schizophrenia. Here we examine the effects of increasing endogenous cannabinoids on dopamine neuron activity in the sub-chronic phencyclidine (PCP) model. Aberrant dopamine system function is thought to underlie the positive symptoms of schizophrenia.

Methods:

Using in vivo extracellular recordings in chloral hydrate–anesthetized rats, we now demonstrate an increase in dopamine neuron population activity in PCP-treated rats.

Results:

Interestingly, endocannabinoid upregulation, induced by URB-597, was able to normalize this aberrant dopamine neuron activity. Furthermore, we provide evidence that the ventral pallidum is the site where URB-597 acts to restore ventral tegmental area activity.

Conclusions:

Taken together, we provide preclinical evidence that augmenting endogenous cannabinoids may be an effective therapy for schizophrenia, acting in part to restore ventral pallidal activity.     

Decreased levels of serum brain-derived neurotrophic factor in drug-naïve first-episode schizophrenia: relationship to clinical phenotypes

Objective

There is accumulating evidence that brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of patients with schizophrenia. Clinical studies show reductions in BDNF in schizophrenic patients treated with first generation antipsychotics or second generation antipsychotics. However, there have been few systematic studies to examine the relationship between BDNF levels and psychopathology in first-episode and drug-naïve patients with schizophrenia.

Materials and methods

Serum BDNF levels were determined using enzyme-linked-immunosorbent assay (ELISA) in the serum of 88 never-medicated first-episode and 90 healthy controls subjects matched for age and gender. The schizophrenia symptomatology and the depressive symptoms were assessed by the positive and negative syndrome scale (PANSS) and the Hamilton rating (HAMD) scale for depression.

Results

The results showed that BDNF levels were significantly lower in first-episode patients with schizophrenia than in healthy control subjects (9.0?±?4.2 ng/ml vs 12.1?±?2.2 ng/ml; F?=?37.6; df?=?1, 176; p?<?0.0001). A significant positive correlation between BDNF levels and PANSS positive subscore was observed (r?=?0.29; df?=?88; p?=?0.008). Furthermore, higher BDNF levels were observed in patients with paranoid subtype of schizophrenia. However, no significant correlation between BDNF and HAMD total score was found.

Conclusion

Low BDNF levels at the onset of psychosis suggest that it may contribute to the pathogenesis of schizophrenia and perhaps, could be a candidate biological marker for positive symptoms.     

Raloxifene adjunctive therapy for postmenopausal women suffering from chronic schizophrenia: a randomized double-blind and placebo controlled trial

Background

Cumulative evidence from epidemiological, preclinical and clinical studies suggests estrogens may have psychoprotective effects in schizophrenic patients. Selective Estrogen Receptor Modulators could have therapeutic benefits in schizophrenia for both sexes without being hazardous to gynecological tissues or having feminizing effects. Few studies have been conducted regarding the effects of raloxifene on postmenopausal women suffering from schizophrenia. We conducted this placebo-controlled trial to compare the add-on effect of raloxifene to risperidone versus risperidone with placebo.

Methods

This was an 8-week, parallel-group, placebo-controlled trial undertaken at two universities affiliated psychiatric Hospitals in Iran. Forty-six postmenopausal women with the definite diagnosis of schizophrenia were enrolled in the study. Patients received risperidone (6 mg/day in 3 divided doses) combined with either placebo (N = 23) or 120 mg/day of raloxifene (N = 23) for 8 weeks. Patients were assessed by a psychiatrist at baseline and at 2 and 8 weeks after the start of medical therapy. Efficacy was defined as the change from baseline to endpoint in score on Positive and Negative Syndrome Scale (PANSS).

Results

For PANSS scores, the main effect comparing two types of intervention was not significant [F (1, 48) = 1.77, p = 0.18]. For positive subscale scores, there was marginal significant interaction between intervention type and time [F (2, 47) = 2.93, p = 0.06] and there was substantial main effect for time [F (2, 47) = 24.39, p = 0.001] within both groups showing reduction in positive subscale scores across the three time periods. In addition, the main effect comparing two types of intervention was significant [F (1, 48) = 3.78, p = 0.02]. On the other hand, for negative subscale scores, the main effect comparing two types of intervention was not significant [F (1, 48) = 1.43, p = 0.23]. For general subscale scores, the main effect comparing two types of intervention was not significant [F (1, 48) = 0.03, p = 0.86].

Conclusions

According to our findings, raloxifene as an adjunctive treatment to risperidone was only superior in improvement of positive symptoms and it was not effective in treating negative and general psychopathology symptoms.

Trial registration

The trial was registered at the Iranian registry of clinical trials: IRCT201205131556N42